Technical Field
This document discloses actuating systems and nozzles for liquid dispensers. More specifically, this document discloses actuating systems for a liquid dispenser that includes a stationary and circular array of nozzles. The disclosed actuating systems are capable of moving an actuator amongst or around the circular array of nozzles before the actuating system stops the actuator at a specific nozzle. The actuating systems then rotate the actuator to open the selected nozzle.
This document also discloses nozzles for multiple liquid dispensers that feature a slider that is movable between a fully closed position and a plurality of open positions, including a fully open position. The disclosed nozzles may be equipped with a sniff back function and a reverse sniff back function that keeps the nozzle full of liquid before, during and after the opening and closing of the nozzle.
Description of the Related Art
Systems for dispensing a plurality of different liquids into a container are known. For example, systems for dispensing paint base materials and colorants into a paint container are known. These paint dispensing systems may use twenty or more different colorants to formulate a paint mixture. Each colorant is contained in a separate canister or package and typically includes its own dispensing pump. In some systems, the colorants and the respective pumps may be disposed on a rotating turntable disposed above a stationary container. In other systems, the colorants may be disposed along one or more stationary horizontal rows disposed above a container disposed on moving platform. Also, in some systems, the colorants may be dispensed through a stationary dispense manifold into a stationary container, wherein the manifold includes a plurality of nozzles.
In a turntable system, the turntable rotates so that the liquid to be dispensed is moved to a position above a stationary container that is being filled. Turntable systems require at least one motor to rotate the turntable, another motor to open and close the nozzles associated with the liquids to be dispensed and separate motors to operate each liquid pump. Further, the motors operating each pump and the canisters containing the liquids are mounted for rotation with the turntable, resulting in a complex and somewhat cumbersome design.
In liquid dispensers using one or more stationary horizontal rows, the container moves laterally to the appropriate colorant/pump for the next dispense. A motor for opening and closing the nozzles associated with each liquid must travel with the container, which also makes for a cumbersome design.
In manifold designs, the container, liquid pumps, liquid canisters and nozzles remain stationary as the liquids are sequentially or simultaneously pumped though individual nozzles held closely together by a manifold block. However, as noted above, some liquid dispensers dispense more than 20 different liquids and it is difficult to design a manifold that can accommodate so many different nozzles in a space-efficient and compact manner. Further, nozzles disposed in manifolds are prone to clogging and dripping, both of which are problematic.
One way in which the precision of a liquid dispensing system is compromised is “dripping”. Specifically, a “leftover” drip may be hanging from a nozzle that was intended for a previous formulation and, with a new container in place under the nozzle, the drop of liquid intended for a previous formulation may be erroneously added to a new formulation. Thus, the previous container may not receive the desired amount of the liquid ingredient and the next container may receive too much.
To solve the drip problem, various scraper and wiper designs have been proposed to scrape any leftover material from an individual nozzle or an entire manifold block after a dispense operation is complete. However, these designs often require one or more different motors to operate the wiper element. Further, the use of a wiper or scraping function may not be practical in a multiple nozzle manifold design, as the liquids from the different nozzles will be cross-contaminated by the wiper or scraper, which would then also contribute to the lack of precision of subsequently produced formulations. Accordingly, improved nozzle designs that address the drip problem are needed.
Another problem associated with dispensing systems that make use of nozzles is clogging. Specifically, nozzle clogging may be experienced with the dispensing of relatively viscous liquids such as tints, colorants, base materials for paints and cosmetic products, certain pharmaceutical ingredients or other liquid materials having relatively high viscosities and/or volatile solvents. The viscous liquids have a tendency to dry and cake onto the end of the nozzles, thereby requiring frequent cleaning in order for the nozzles to operate effectively. For example, when a liquid or slurry material dries on a nozzle, the dispense stream may be misdirected causing the liquid or slurry to miss the container being filled. This problem is particularly prevalent in the dispensing of colorants or tints. While some mechanical wiping or scrapping devices are available, these devices are not practical for multiple nozzle manifold systems for the reasons set forth above and the scraper or wiper element must be manually cleaned anyway. Further, nozzles have also been known to clog entirely when exposed to air for an extended period, which renders wiping or scrapping devices ineffective.
Another problem associated with liquid dispensing systems is air entering the nozzle during the opening or closing of the nozzle. For example, when a nozzle is opened, air may be free to enter the nozzle outlet and consume some of the interior volume of the nozzle through which the liquid flows. Some dispensing systems may attempt to account for air in the nozzle during calibrations, but the results may be inconsistent. Other systems may require the nozzle to be primed with liquid before a dispense, which is time consuming and wasteful. Regardless, the presence of air in a nozzle compromises the accuracy of the dispense and improved nozzle designs are needed that address the air problem.
Nozzles for liquid dispensers of the type described above typically have two positions—open and closed. Because of the high degree of precision required by some applications, a nozzle design that can be opened fully or partly by a motorized mechanism would be very beneficial. Such a nozzle design would enable a fast dispense rate when in a fully open position and slower dispense rates when in partially open positions. Such an improved nozzle design would need to address the problem of air entering the nozzle between dispenses as well.
Accordingly, a need exists for improved multiple liquid dispensers and actuation systems that are less cumbersome and complex. A need also exists for improved nozzle designs that are not prone to clogging, that are not prone to allowing air into the nozzle between dispenses and that enable dispensing through the nozzle in not only a fully open position but through a plurality of partially open positions as well.